Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 020240 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1040 PM EDT WED JUL 1 2015 .SYNOPSIS... A WEAK SURFACE COLD FRONT IS DISSIPATING AS IT DROPS SOUTHWARD ACROSS CENTRAL PENNSYLVANIA THIS EVENING. THIS BOUNDARY WILL SEPARATE DRIER AIR TO THE NORTH FROM MOIST AND UNSTABLE AIR TO THE SOUTH...AND GRADUALLY LIFT BACK TO THE NORTH AS THE WEEK WEARS ON. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE ACROSS SOUTHERN PENNSYLVANIA BY FRIDAY...AND ACROSS THE REMAINDER OF CENTRAL PENNSYLVANIA ON THE FOURTH OF JULY. DRIER AIR WILL RETURN SOUTHWARD ON SUNDAY AND MONDAY AS AN UPPER LEVEL RIDGE BRIEFLY BUILDS OVER THE NORTHEASTERN UNITED STATES EARLY NEXT WEEK. && .NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
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1030 PM UPDATE... SHORT WAVE OVER LOWER MI ENHANCING HIGH/MID CLOUDS AS THEY NEAR PA. BUT THEY ARE RUNNING INTO THE RIDGE. TEMPS ON TRACK. FOG IS MENTIONED APPROPRIATELY IN THE FORECAST PER THE LATEST CLOUD TRENDS AND T/TD SPREADS. 830 PM UPDATE... DEWPOINTS ONLY INCHING DOWN AS THE BOUNDARY HAS SLOWED TO A CRAWL OVER THE CENRAL COS. BUT ALL IS ON TRACK. HIGH CLOUDS UPSTREAM COULD KEEP THE SKY LESS THAN CLEAR OVERNIGHT...ESP IN THE WEST. THAT COULD ACTUALLY HELP THE FOG/LOW CLOUDS FROM BECOMING TOO BAD - BUT WILL NOT DROP IT SINCE DEWPOINTS STILL NEAR 60F AND UPSLOPE NOT KIND TO THE WESTERN MTNS. 6 PM UPDATE... DRY AIR WINNING OUT AND SHOWERS ARE GONE. WILL HOLD A SLIGHT CHC IN THE FAR NE FOR ANOTHER 2-3 HRS. THE CONVERGENCE ALONG THE BOUNDARY SEEMS TO HAVE WASHED AWAY. MDLS DO HANG ONTO LOW LEVEL MOISTURE IN THE ALLEGHENIES AS THE HIGH PRESSURE BUILDS. SO FOG AND SOME LOW CLOUDS ARE STILL EXPECTED TO FORM THROUGH THE NIGHT. PREV... VISIBLE LOOP INDICATES FRONTAL BOUNDARY EXTENDING FROM THE ENDLESS MOUNTAIN REGION IN NORTHEAST PA TO THE WEST CENTRAL MOUNTAINS... DENOTED BY A BROKEN LINE OF SHOWERS. LAST FEW FRAMES OF REGIONAL RADAR MOSAIC INDICATE A FEW HEAVIER SHOWERS POPPING UP ALONG THE FRONT WEST OF THE ALLEGHENIES...IN A RICHER MOISTURE ENVIRONMENT WHERE SFC DEWPOINTS ARE IN THE LOWER 60S. HI RES NEAR TERM MODELS INDICATE REMAINING SHOWERS DYING OVER THE NEXT FEW HOURS DUE TO DRY AIR ALONG AND EAST OF THE ALLEGHENIES (SFC DEWPOINTS IN THE 50S) AND DOWNSLOPING WSW BOUNDARY LAYER FLOW. WEAK 1017 MB RIDGE OF HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES TONIGHT...WITH LOWER DEEP LAYER MOISTURE LYING ACROSS THE REGION TONIGHT. THIS WILL BRING FAIR WEATHER AND DECREASING TO CALM WINDS...PROMOTING FOG DEVELOPING LATE TONIGHT AND EARLY THURSDAY MORNING. SOME COULD BE LOCALLY DENSE IN THE DEEP NORTHERN VALLEYS.
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&& .SHORT TERM /8 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... FAIR WEATHER WILL CONTINUE ON THURSDAY THANKS TO WEAK HIGH PRESSURE TRAVERSING AREAS TO OUR NORTH. MOISTURE BOUNDARY ALONG AND SOUTH OF THE MASON DIXON LINE WILL PROMOTE AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT OVER THE HIGHER TERRAIN OF NORTHERN MD AND WV...EXTENDING INTO THE LAUREL HIGHLANDS. COVERAGE WILL BE ISOLD TO SCT. MAX TEMPS SHOULD RANGE FROM THE LOWER 70S NORTH TO THE LOWER 80S SOUTHEAST. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THE MODELS REMAIN IN FAIR AGREEMENT WITH THE DRIER...NORTHWESTERLY FLOW KEEPING THE MOISTURE SOUTH OF THE BORDER FRIDAY INTO SATURDAY. DESPITE MINOR TIMING DIFFERENCES AMONG MED RANGE MDLS...THE OVERALL PATTERN APPEARS FAIRLY CERTAIN. MEAN UPPER LVL TROF WILL REMAIN CENTERED WEST OF PA...RESULTING IN SOME OPPORTUNITIES FOR RAIN. ECENS/GEFS INDICATE THE BEST CHC FOR SHOWERS WILL ACCOMPANY PASSAGE OF SHORTWAVES SAT AFTERNOON AND TUE. THERE IS A CHANCE ON FRIDAY AFTERNOON AS THE TROUGH DIGS DOWN AS IT PROPAGATES EASTWARD. A STRONG RIDGE SHOULD REMAIN ITSELF GEFS/ECENS MEAN 8H TEMPS IMPLY TEMPS FAIRLY CLOSE TO AVERAGE FOR EARLY JULY. SAT IS LIKELY TO BE A BIT COOL DUE TO CLOUDS/SHOWERS AND LOW LVL EASTERLY FLOW. HOWEVER...SW FLOW IN ADVANCE OF AN APPROACHING COLD FRONT IS LIKELY TO PUSH TEMPS A BIT ABV AVERAGE BY TUES OF NEXT WEEK. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... 00Z TAFS GOING OUT IN A FEW MINUTES. MAINLY A SCT-BKN AREA OF CU ACROSS CENTRAL PA. STILL HAZY OUT...BUT BULK OF SMOKE SOUTH OF OUR AREA NOW...CAN SEE IT FROM CENTRAL CANADA SE TO SOUTHERN OH...ON THE OBS AND VISIBLE SATELLITE PICS. YESTERDAY IT WAS FURTHER NORTH ACROSS OUR AREA. EARLIER DISCUSSION BELOW. NOT MUCH ON RADAR FOR A CHANGE. 21Z TAFS SENT. MADE SOME CHANGES...WHICH I WILL USE ON THE 00Z PACKAGE. EXPECT THE GUSTY WEST TO NW FLOW TO WEAKEN BY SUNSET. GIVEN THE WET CONDITIONS OF RECENT TIMES...AND THAT TEMPERATURES ARE EXPECTED TO DROP TO THE DEWPOINT...CROSS OVER TEMPERATURE...EXPECT SOME FOG AND LOW CIGS TO FORM LATE. ALSO THE HIGH WILL BE NEARLY OVERHEAD LATE TONIGHT. EXPECT CONDITIONS TO IMPROVE THU MORNING...GIVEN THE STRONG EARLY JULY SUN. OUTLOOK... THU...MAINLY VFR. ISOLATED TSRA MAINLY SOUTH OF I-80. FRI...MAINLY VFR. SAT-MON...MAINLY VFR...BUT A CHANCE SHRA/TSRA...MAINLY ACROSS THE SOUTH. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/DEVOIR NEAR TERM...DANGELO/DEVOIR SHORT TERM...DEVOIR LONG TERM...FITZGERALD/CERU AVIATION...MARTIN

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